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1.
A general approach to the synthesis of 5,7-disubstituted indoles has been developed based upon a highly selective lithium-bromine exchange reaction at the 7-position when 1-alkyl-5,7-dibromoindoles were treated with t-BuLi in ether. The resulting 5-bromo-7-lithiated indoles could react with various electrophiles to afford 5-bromo-7-substituted indoles (6) upon work-up. Without isolation of 6, the intermediates thus obtained could be exposed to a second lithium-bromine exchange reaction in a one-pot procedure and further reacted with various electrophiles to afford 5,7-disubstituted indoles (1). 相似文献
2.
Wim Van Snick 《Tetrahedron》2009,65(41):8497-4184
Efficient cyclization reactions of 5-aminobenzothiophene derivatives with internal and terminal acetylenes, giving 7- and 8-substituted thieno[3,2-e]indoles, are described. The reaction of 4-iodo-5-(methylsulfonamido)benzothiophene with terminal alkynes gave 7-substituted thienoindoles using general Sonogashira reaction conditions. Reaction of 5-amino-4-iodobenzothiophene with internal acetylenes, using Larock's heterocyclization reaction conditions, gave 7,8-disubstituted thieno[3,2-e]indoles. 相似文献
3.
Akira Kasahara Taeko Izumi Satoshi Murakami Kazuhiro Miyamoto Toshimi Hino 《Journal of heterocyclic chemistry》1989,26(5):1405-1413
The palladium-catalyzed cross-coupling reaction of 2-bromonitrobenzenes or 2-bromoacetanilides with ethylene has been used to produce a variety of substituted indoles. The mild reaction conditions and selectivity inherent in the coupling reaction have been utilized to produce regiochemically pure 4-, 5-, 6-, and 7-substituted indoles. 相似文献
4.
A comprehensive library of N- or 1-substituted indoles was formed by conjugate additions of indoline with Michael acceptors followed by an oxidation step. Using N-substituted indoles as key Michael donors, the synthesis of 1,3-disubstituted indoles was also accomplished. 相似文献
5.
D. A. Skladchikov A. A. Fatykhov R. R. Gataullin 《Russian Journal of Organic Chemistry》2014,50(1):48-53
7-Bromo-, 7-phenylethynyl-, 7-azido-, 7-nitro-, and 5,7-dinitro-substituted N-acetyl-1,3a,4,8b-tetrahydrocyclopenta[b]indoles have been synthesized starting from anilines and 3-chlorocyclopentene. The NMR spectra of N-acetyl-7-nitro-1,3a,4,8b-tetrahydrocyclopenta[b]indoles displayed no signal doubling typical of the other 7-substituted derivatives. 相似文献
6.
O. N. Chupakhin T. L. Pilicheva I. Ya. Postovskii N. A. Klyuev 《Chemistry of Heterocyclic Compounds》1975,11(5):615-618
2-Quinazolone reacts with various π-surplus systems (indoles and pyrroles) to give 3,4-dihydro-4-substituted 2-quinazolones. These compounds are capable of oxidation to 4-substituted 2-quinazolones. o-Carbamidobenzylideneurea gives identical products in these reactions. 相似文献
7.
The synthesis of 2-, 3-, 4-, and 6-substituted pyrido[2,3-b]indoles (α-carbolines) by palladium-catalyzed cross-coupling reactions from the corresponding halopyrido[2,3-b]indoles is described. A sequential and a one-pot chemoselective double Suzuki-Miyaura coupling route is presented for the synthesis of symmetrically and unsymmetrically disubstituted pyrido[2,3-b]indoles. 相似文献
8.
Maksim A. Kolosov Elena H. Shvets Dmitriy A. Manuenkov Sergey A. Vlasenko Irina V. Omelchenko Svetlana V. Shishkina Valeriy D. Orlov 《Tetrahedron letters》2017,58(12):1207-1210
6-Unsubstituted 7-R-4,7-dihydro-1,2,4-triazolo[1,5-a]pyrimidines (R = H or Me) were synthesized via two pathways: (a) deacylation of the corresponding 5-acetyl Biginelli-like precursors in KOH/H2O and (b) reduction of the corresponding 1,2,4-triazolo[1,5-a]pyrimidines using LiAlH4. The products could be easily formylated at position 6, which is promising for the further synthesis of functionalized 6-substituted derivatives of 4,7-dihydro-1,2,4-triazolo[1,5-a]pyrimidines. In contrast, 6-acetyl-7-(4-(N,N-dimethylaminophenyl))-5-methyl-4,7-dihydro-1,2,4-triazolo[1,5-a]pyrimidine undergoes a cascade process in KOH/H2O, leading to the formation of a 4,5,8,9-tetrahydro[1,2,4]triazolo[5,1-b]quinazoline derivative. 相似文献
9.
[reaction: see text] Although the indole N-phosphinoyl derivative 4 undergoes n-BuLi deprotonation/electrophile quench to afford C-7-substituted products, its deprotection requires harsh conditions. On the other hand, the N-amide 12, upon sequential or one-pot C-2 metalation, silylation, C-7 metalation, and electrophile treatment, furnishes indoles 7 in good overall yields. In combination with the Suzuki-Miyaura protocol, C-7 aryl (heteroaryl)-substituted indoles 14 and 16 are obtained, including hippadine and pratosine, members of the pyrrolophenanthridone alkaloid family. 相似文献
10.
Subhasish Biswas 《Tetrahedron》2010,66(39):7781-7786
DABCO-mediated Morita-Baylis-Hillman reactions of several 1-substituted-indole-2-carboxaldehydes are disclosed. It was discovered that carboethoxy or tert-butoxycarbonyl groups installed at N-1 undergo cleavage under the reaction conditions to afford 2-substituted indoles. Utility of the N-substituted adducts for preparing a variety of annulated indoles has been exemplified. 相似文献
11.
A simple tandem Wittig reaction-reductive decarboxylation route is established for the synthesis of indoles from commercially available o-nitrobenzaldehydes and a stable phosphorane. The method allows access to indoles in a very fast manner without involving any metal or expensive reagents or inert atmosphere. Also 2-substituted indoles are obtained which forms an important core of many biological active compounds. 相似文献
12.
Mohit L. Deb Bhaskar Deka Iftakur Rahman Pranjal K. Baruah 《Tetrahedron letters》2018,59(50):4430-4433
Here we report l-proline catalyzed 3-component reaction of indoles, aldehydes and N-substituted anilines in water as solvent at room temperature for the synthesis of 3-(α,α-diarylmethyl)indoles. The reaction is in fact a Michael addition of N-substituted anilines to alkylideneindolenines. The reaction is very clean, high yielding and having broad substrate scope. A tentative mechanism is proposed. 相似文献
13.
Shambabu J. MaddiralaVidya S. Gokak Sharanabasava B. RajurLinganagouda D. Basanagoudar 《Tetrahedron letters》2003,44(30):5665-5668
Unlike the migration of a methyl group observed in the ZnCl2 or acetic acid-catalysed indolisation of phenylhydrazones, dry ethanolic HCl catalysed indolisation of 2,6-dimethyl- and 2,4,6-trimethylphenylhydrazones of various substituted butane-2,3-diones and ethyl pyruvates yields 7-methyl- and 5,7-dimethyl-3-substituted indoles indicating elimination of an ortho-methyl group during indolisation. 相似文献
14.
《Tetrahedron letters》2019,60(43):151185
A convenient protocol for one-pot synthesis of thieno[3,2-b]indoles, bearing aromatic, thien-2-yl or styryl fragments at C-2 position, from easily accessible 5-substituted 3-aminothiophene-2-carboxylates using the Fischer indolization reaction, was developed during this study. Two main steps of this approach are the saponification of the starting 3-aminoesters with sodium hydroxide and next treatment of the crude 3-aminoacids sodium salts with arylhydrazines in glacial acetic acid solution. The latter step includes in situ decarboxylation of the freed 3-aminothiophene-2-caboxylic acids to the 3-aminothiophenes and their acid promoted reaction with arylhydrazines to initially form arylhydrazones of 5-substituted thiophene-3(2H)-ones, which smoothly cause indolization to afford the desired thieno[3,2-b]indoles. 相似文献
15.
Paul S Chotana GA Holmes D Reichle RC Maleczka RE Smith MR 《Journal of the American Chemical Society》2006,128(49):15552-15553
Ir-catalyzed borylation of 2-substituted indoles selectively yields 7-borylated products in good yields. N-Protection, required for previous functionalizations of 2-substituted indoles, is unnecessary. 相似文献
16.
Yu Chen 《Tetrahedron》2009,65(44):8908-8915
A microwave-assisted, one-pot, three-component coupling reaction for the synthesis of indoles has been developed. The reaction is carried out in two steps under standard Sonogashira coupling conditions from an N-substituted/N,N-disubstituted 2-iodoaniline and a terminal alkyne, followed by the addition of acetonitrile and an aryl iodide. A variety of polysubstituted indoles have been prepared in moderate to excellent yields using the present method. 相似文献
17.
Robin D. Clark 《Journal of heterocyclic chemistry》1983,20(5):1393-1395
N-substituted 4-(2-morpholinyl)indoles were prepared from 1-(t-butoxycarbonyl)-4-acetylindole (7) which was itself prepared from 4-cyanoindole. Bromination of ketone 7, followed by reaction with amines and subsequent sodium borohydride reduction, gave amino alcohols. These were converted to α-chloro amides that were cyclized to lactams. Lithium aluminum hydride reduction served both to remove the t-BOC protecting group and to reduce the lactams to the 4-(2-morpholinyl) indoles. 相似文献
18.
Eric Duval 《Tetrahedron letters》2004,45(28):5411-5413
A new route to substituted β-carbolines and carbazoles is described. Diketoindole intermediates, prepared by Friedel-Crafts acylations of 3-substituted indoles, have been converted to 3-hydroxycarbazoles and β-carbolines in good yields, 51-96% and 82-97%, respectively. This method also allows for the formation of 4-substituted β-carbolines. The application of this methodology to the synthesis of the natural products hyellazole and 6-chlorohyellazole is also described. 相似文献
19.
Lei Zhang Junyu Chen Jinkang Chen Licheng Jin Xiangyun Zheng Xinpeng Jiang Chuanming Yu 《Tetrahedron letters》2019,60(15):1053-1056
A highly regioselective synthesis of 2-substituted indoles was realized through Ir(III)-catalyzed CH functionalization of N-phenylpyridin-2-amines followed by the reaction with sulfoxonium ylides and intramolecular cyclization under mild conditions. The reaction completed with broad range of substrate scopes and gave various 2-substituted indoles in up to 98% yields. 相似文献
20.
Takashi Miyagi 《Tetrahedron letters》2004,45(33):6303-6305
Lithium trimethylsilyldiazomethane smoothly reacted with N-tosyl-o-acylanilines to give 3-substituted indoles in good to high yields. 相似文献